Is a 'retweet' an endorsement?

Occasionally on Twitter I am asked to retweet something; a competition, a charitable cause, a tweet to raise awareness. By doing so, I believe I am endorsing the information in the tweet or accompanying link - I am showing my support. More often than not, I try to add a few words into the retweet to express my opinion. This is easier using a third party client such as Tweetdeck as the Twitter web only allows a direct retweet with no alteration to the original text.

This is where endorsement issues can arise.
A 19-year old Councillor in Staffordshire has been suspended after retweeting a post about genital mutilation for teenage mothers. Mr Taylor says he retweeted the post to raise awareness whilst opposition Councillors believe that the retweet endorsed the practice. Without reading tweets either side of this action, the intent remains a grey area and, in a busy twitter timeline, previous and subsequent tweets can be lost.

Can the same be said for the recent interest in an social media blogging tool called Triberr? The idea behind Triberr is that a group of bloggers form a supportive "tribe" and tweet out each others blog posts to help with promotion. On the surface that activity sounds like a really good idea but Triberr tweets are automatic [EDIT: please see comments for clarification from Triberr]. What if a member of my tribe wrote something that I didn't agree with? Does the auto-tweet in my name mean that I support that view point?

I would much prefer someone to read my blog post and decide whether it should be shared on social media platforms on its own merits. And even if the content is disagreeable then the luxury of freedom of speech allows comment to that effect.

If you see someone retweeting something, do you presume that they support the information in that tweet?